A matter of degree : mid-career professional training for museum workers in the United States & Great Britain

What are the differences between the continuing education programs for museum workers in the United States and Great Britain, and what do these distinctions reveal about the ways in which the role of the museum worker is perceived in these respective countries?;This study will: (1) analyze the literature surrounding these questions, literature ranging in topics from the sociology of professions to descriptions of mid-career training options, (2) compare and contrast the museums, museum studies programs, and continued learning schemes for museologists, and, finally, (3) examine the differences and similarities between two representative programs, one for each country: the Seminar for Historical Administration and the Diploma Scheme of the Museums Association in Great Britain. From these comparisons both general and specific, the investigation will conclude with an interpretation of the differences in so far as they shed light on the varying perceptions of the museum worker in the United States and Great Britain.;In the United States, museum workers are exposed to a seemingly unlimited array of mid-career training options, a veritable smorgasbord of professional learning opportunities of varying quality and usually offered by agencies quite independent of the academy. Contest mobility prevails. The programs are responsive to an ever-changing market. While, in Great Britain, only a few options are available, most notable is the diploma scheme with its university affiliations. When compared to the American system, a semblance of sponsored mobility prevails, and one is struck by the limited, single-level and insulated nature of the programs available. This dissertation identifies these distinctions and expands on their significances as they pertain to current perceptions of the museum workers in each country

Leukotriene B4 stimulates the release of arachidonate in human neutrophils via the action of cytosolic phospholipase A2

AbstractLeukotriene B4 (LTB4) is a potent lipid mediator of inflammation and is involved in the receptor-mediated activation of a number of leukocyte responses including degranulation, superoxide formation, and chemotaxis. In the present research, stimulation of unprimed polymorphonuclear leukocytes (neutrophils) with LTB4 results in the transient release of arachidonate as measured by mass. This release of arachidonate was maximal at an LTB4 concentration of 50–75 nM and peaked at 45 s after stimulation with LTB4. The transient nature of this release can be attributed, in part, to a fast (<60 s) metabolism of the added LTB4. Moreover, the inhibition of the reacylation of the released arachidonate with thimerosal results in greater than 4-times as much arachidonate released. Thus, a rapid reacylation of the released arachidonate also contributes to the transient nature of its measured release. Multiple additions of LTB4, which would be expected to more closely resemble the situation in vivo where the cell may come into contact with an environment where LTB4 is in near constant supply, yielded a more sustained release of arachidonate. No release of [3H]arachidonate was observed when using [3H]arachidonate-labeled cells. This indicates that the release of arachidonate as measured by mass is most probably the result of hydrolysis of arachidonate-containing phosphatidylethanolamine within the cell since the radiolabeled arachidonate is almost exclusively incorporated into phosphatidylcholine and phosphatidylinositol pools under the non-equilibrium radiolabeling conditions used. Consistent with the role of cytosolic phospholipase A2 (cPLA2) in the release of arachidonate, potent inhibition of the LTB4-stimulated release was observed with methylarachidonylfluorophosphonate, an inhibitor of cPLA2 (IC50 of 1 μM). The bromoenol lactone of the calcium-independent phosphospholipase A2. failed to affect LTB4-stimulated release of arachidonate in these cells

Inhibition of Immune Complex-Induced Inflammation by A small Molecular Weight Selectin Antagonist

The anti-inflammatory effect of a small molecular weight antagonist of P- and E-selectin-dependent cell adhesion was examined. The glycolipid sulphatide was shown to block the adherence of thrombin-activated rat platelets to HL-60 cells. This interaction is known to be dependent on P-selectin. The rat dermal reverse passive Arthus reaction was used to assess the effect of sulphatide on a neutrophil dependent inflammatory response. Sulphatide dosedependently blocked both the vascular permeability increase and cell infiltration after intraperitoneal administration. These results show that a small molecular weight compound which blocks P- and E-selectin dependent adhesion in vitro can effectively block the inflammation due to immune complex deposition. A compound with this type of profile may have therapeutic potential in the treatment of immune complex mediated diseases

SDSS J210014.12+004446.0: A New Dwarf Nova with Quiescent Superhumps?

We report follow-up observations of the Sloan Digital Sky Survey Cataclysmic Variable SDSS J210014.12+004446.0 (hereafter SDSS J2100). We obtained photometry and spectroscopy in both outburst and quiescent states, providing the first quiescent spectrum of this source. In both states, non-sinusoidal photometric modulations are apparent, suggestive of superhumps, placing SDSS J2100 in the SU UMa subclass of dwarf novae. However, the periods during outburst and quiescence differ significantly, being 2.099 plus or minus 0.002 hr and 1.96 plus or minus 0.02 hr respectively. Our phase-resolved spectroscopy during outburst yielded an estimate of about 2 hr for the orbital period, consistent with the photometry. The presence of the shorter period modulation at quiescence is unusual, but not unique. Another atypical feature is the relative weakness of the Balmer emission lines in quiescence. Overall, we find a close similarity between SDSS J2100 and the well-studied superhump cataclysmic Variable V503 Cygni. By analogy, we suggest that the quiescent modulation is due to a tilted accretion disk -- producing negative superhumps -- and the modulation in outburst is due to positive superhumps from the precession of an elliptical disk.Comment: 6 pages, 5 eps figures, accepted by PASP Dec. 16th, 200

SDSS J210014.12+004446.0 - dwarf nova with negative and positive superhumps

We report the results of 67h of CCD photometry of the recently discovered dwarf nova SDSS J210014.12+004446.0. The data were obtained on 24 nights spanning a month. During this time we observed four ordinary outbursts lasting about 2-3 days and reaching an amplitude of ~1.7 mag. On all nights our light curve revealed persistent modulation with the stable period of 0.081088(3) days. These humps were already observed on one night by Tramposch et al. (2005), who additionally observed superhumps during a superoutburst. Remarkably, from scant evidence at their disposal they were able to discern them as negative and positive (common) superhumps, respectively. Our period in quiescence clearly different from their superhump period confirmed this. Our discovery of an additional modulation, attributed by us to the orbital wave, completes the overall picture. Lack of superhumps in our data indicates that all eruptions we observed were ordinary outbursts. The earlier observation of the superhumps combined with the presence of the ordinary outbursts in our data enables classification of SDSS J2100 as an active SU UMa dwarf nova. Additionally, we have promoted SDSS J2100 to the group of cataclysmic variables exhibiting three periodic modulations of light from their accretion discs. We updated available information on positive and negative superhumps and thus provided enhanced evidence that their properties are strongly correlated mutually as well as with the orbital period. By recourse to these relations we were able to remove an alias ambiguity and to identify the orbital period of SDSS J2100 of 0.083304(6) days. SDSS J21000 is only third SU UMa dwarf nova showing both positive and negative superhumps. Their respective period excess and deficit equal to 4.99(3)% and -2.660(8)%, yielding the mass ratio q=0.24.Comment: 10 pages, 9 figures, accepted for publication in MNRA

Photoacoustic hygrometer for icing wind tunnel water content measurement: design, analysis and intercomparison

This work describes the latest design, calibration and application of a near-infrared laser diode-based photoacoustic (PA) hygrometer developed for total water content measurement in simulated atmospheric freezing precipitation and high ice water content conditions with relevance in fundamental icing research, aviation testing, and certification. The single-wavelength and single-pass PA absorption cell is calibrated for molar water vapor fractions with a two-pressure humidity generator integrated into the instrument. Laboratory calibration showed an estimated measurement accuracy better than 3.3 % in the water vapor mole fraction range of 510–12 360 ppm (5 % from 250–21 200 ppm) with a theoretical limit of detection (3σ) of 3.2 ppm. The hygrometer is examined in combination with a basic isokinetic evaporator probe (IKP) and sampling system designed for icing wind tunnel applications, for which a general description of total condensed water content (CWC) measurements and uncertainties are presented. Despite the current limitation of the IKP to a hydrometeor mass flux below 90 gm-2s, a CWC measurement accuracy better than 20 % is achieved by the instrument above a CWC of 0.14 g m−3 in cold air (−30 ∘C) with suitable background humidity measurement. Results of a comparison to the Cranfield University IKP instrument in freezing drizzle and rain show a CWC agreement of the two instruments within 20 %, which demonstrates the potential of PA hygrometers for water content measurement in atmospheric icing condition